Smiling in photographs: childhood similarities between sexes become differences constant in adulthood.

Contemporary published photographs of 1639 children, 200 older teenagers, and 304 adults in North America were analyzed for the smiling pattern (full, partial, or none) exhibited by individuals by sex. For each of the three age groups and for both sexes, most individuals posed with a full smile. No statistically significant differences in smiling pattern were present between the sexes for photographs of children at preschool and grade-school age.

Determination of genetic sex in chinook salmon (Oncorhynchus tshawytscha) using the male-linked growth hormone pseudogene by real-time PCR.

This study used a real-time quantitative polymerase chain reaction (qPCR) method based on the growth hormone pseudogene (GHp) in chinook salmon (Oncorhynchus tshawytscha) to determine genetic sex. The GHp is present as a single copy in the genome of the male chinook salmon but is absent in the female, providing a means of using this real-time qPCR method to discriminate genetic sex. Comparisons between genomic DNA samples from 2 geographically distinct populations of chinook salmon (Columbia River, Washington, and Yukon River, Alaska) showed, within each population examined, that the males were clearly differentiated from the females.